The paths where created the same way; choosing the path not typing them in.
There are no obvious error messages. Where would I look for them?

When I chose /sharedfoldes/whale/.config/plex — /sharedfolders/whale/.config/plex/Library/ — is created by Plex container, when it is run.

You can look in the Log for the container, it is available in the Docker GUI.

OK, some more questions.

You have set PGIG 100 and PUID 1001. Are those real existing users on your system or did you read about using those somewhere and just put them in? Look in the Log to see what user and group the container is running as.

What is the ownership and permissions on the storage drive(s) you are trying to write these items to?

The only change I made from working state to broken state is the pointer to the .config directory.

This is from the container log via the Docker GUI:
#####################################################
# Login via the webui at http://<ip>:32400/web #
# and restart the docker, because there was no #
# preference file found, possibly first startup. #
#####################################################

I suspect it is the + in the folder permissions, but I do not know what the + is. Something to do with ACLs?
drwxr-xr-x 3 docker users 4.0K Mar 17 22:58 Library(working)
drwxrwxrwx+ 3 docker users 4.0K Mar 20 08:19 Library(broken)

Like so: /srv/7911fa44-a322-442c-a434-6c2ad2f3b1ff/whale/.config/plex/ ?
This is wat I got:
####################################################
# Login via the webui at http://<ip>:32400/web #
# and restart the docker, because there was no #
# preference file found, possibly first startup. #
#####################################################

This all works fine if I create /.config/plex in the /home/docker/, but when I create /.config/plex on the data drive the container does not populate it fully.
Do you think it may have to do with permissions?

I am saying that .config is really a misnomer for the directory name. In a standard install it would not be a name preceded with a dot, nor would it be called config. It really is not a docker configuration file, it's the PMS metadata database.

Whatever you call that directory, it must be owned by the user and group that PMS is running as.

fred:users is the user:group that all my dockers run as and their configurations set these as PUID and PGID with the numerical equivalents for the user and group.

The folowing are directories on one of several 3TB disks I have:
drwxr-sr-x 3 fred users 4096 Mar 12 16:02 plexmediaserver-dockered (This is the Plex Media Server Database. /config in the docker container path points here)
drwxr-sr-x 3 fred users 4096 Mar 22 10:17 plexmediaserver-transcode (This is where transcode temp files are written to by the PMS docker. /transcode in the docker container path points here)

The following is one of several mergerfs mountpoints that exist on one of the 3TB disks. The actual data is spread out over a pool 4x 3TB disks:
drwxr-sr-x 2370 fred users 126976 Mar 21 20:50 movies (This is a mergerfs pool mountpoint for movies. /data/movies in the docker container path points here)

All my media directories and files are owned by fred:users (movies, music, tv-series) and have permissions of 2755. All the files within those directories have permissions of 0644.

Well this(OMV) has been a learning experience for me. I do appreciate the help I get here. Tricky to ask questions when I am limited in understanding the subject. This is my first venture into Docker. I have been doing my learning on my secondary server. It will be a week before I come back to that computer.
In the meantime I realize that my primary server has a 220GB M.2 boot drive. I am thinking it best to keep Docker and PLEX needs on that big fast drive. Which I got up and running last night. My next adventure will be setting-up haugene/transmission-openvpn. This is overwhelming for me as I know little about OpenVPN(VPN for that matter), Docker, and Transmission with hopes of having it dance with Sonarr. So expect a bunch of questions there.

PMS is your first docker image? Gratulation? PMS was my fourth docker image and it was the hardest to get it to run.
There're some things you have to do.
First check in the fstab file (via ssh to your server => nano /etc/fstab) and remove the "noexec" command from your mounted drive where you want to store the config files. Why? You can't watch any videos via Browser over the internet because Plex can't use his codec folder. Don't know why here I found the solution.
I also have created a Config-Dir on the second partition of my system drive (512GB SSD - first I've installed Debian Stretch and partitioned it while installation, afterwards I've installed OMV over it). Withchmod -R 777 /sharedfolder/Folder-of-config/PMS-configs
andchown -R dockeruser:user /sharedfolders/Folder-of-config/PMS-configs
I changed permissions. My username for Docker is "Wuzzi" which has normal user rights and also rights to write/read to the shared smb-folders which contain my data.

Another tricky point is the iGPU-transcoding (hardware transcoding of the intel GPU). To get it run you have to pass through the GPU to your docker. With the command under "extra-args"

--device=/dev/dri

you can do that trick. BUT! There's another problem to solve. You have to change permissions of /dev/dri to the dockeruser too (in my case: Wuzzi:users). But here it's very tricky because when you change permissions, after reboot the old settings are back (root:root). How to solve this? With a script under /usr/local/bin and the name permissions.sh. That's my script (for the intel GPU and my DVB-S cards)

Shell-Script

#!/bin/sh

chown -R Wuzzi:users /dev/dvb/adapter0

chown -R Wuzzi:users /dev/dvb/adapter1

chown -R Wuzzi:users /dev/dvb/adapter2

chown -R Wuzzi:users /dev/dvb/adapter3

sleep 1

chmod -R 666/dev/dvb/adapter0

chmod -R 666/dev/dvb/adapter1

chmod -R 666/dev/dvb/adapter2

chmod -R 666/dev/dvb/adapter3

sleep 1

chown -R Wuzzi:users /dev/dri/card0

chown -R Wuzzi:users /dev/dri/renderD128

sleep 1

chmod -R 666/dev/dri/card0

chmod -R 666/dev/dri/renderD128

sleep 1

exit0

Display All

and withchmod a+x /usr/local/bin/permissions.sh
you make it executable.
But that's not all. Under /etc/systemd/system I've created the following service-script with: nano set-permissions.service

Source Code

[Unit]

After=network.target

[Service]

ExecStart=/usr/local/bin/permissions.sh

[Install]

WantedBy=multi-user.target

and with the command

systemctl enable set-permissions.service

and after a reboot of the server this service runs in the background. After every reboot/hibernate/standby/power on the above script is executed and the permissions are set.